Fuel-handling system



Oct. 2l, 1930. R. D. DE woLF v v1,778,755

` FUEL HANDLING SYSTEM Filed Aug'. l, 1925 By .V

l KAITORNEYS.

Patented oct. 21, 1930 UNITED STATES PATENTA OFFICE ROGER D. DE WOLF, OF ROCHESTER, NEW YORK, AssIGNoE To coMBUs'rroN ENGINEER- ING CORPORATION, OE NEW YORK, N. Y., A CORPORATION or NEW YORK Application led August 1, 192,5. Serial No. 47,419.

sorbed by the air in the system to such an eK- f.

tent that the pulverized coal will pack and tend to clog up the passages. Q

My invention, therefore, has as its primary object the provision of a fuel handling system wherein the `Water-content of the fuelconveying air is limited to such a degree as to keep the system dry enough for efcient op-V eration. i

Another advantage of my invention resides in the fact that the'coal as delivered to the pulverizer need notbe so carefully or thoroughly dried as heretofore since the dryingv ofthe system can be adjusted as necessary by a simple adjustment ofcertain valves provided for the purpose. I aim also by my invention to utilize in an economicaljinannerv any and all air draw-nn from the return line of thesystem. The utilization of this air is of value for the reason .that it still carries a certain amount of coal dust after it leaves the` separator.

VHow the foregoing advantages, andothers -which will no doubt occur to those skilled in the art, are obtained, will appear from the following description, reference being had to the accompanyingdrawing which illustrates somewhat bodying my invention.

illustrated and designate, as follows:`

At, the bottom' is mill or pulverizer 3 which receives fuel in lump form, or run-of- ;mine.coal, through the conduitl 2. The pulverized fuel is carried from the mill I h1'o 11ghy the pipe 4, to an exhauster 5, by which 1t is forced, in -a stream of air,throughrthe Econduit 6 to a separator 7. i The fuel, separated from the carrying air,-

isdeposited in thevbin 8 from where it may diagrammatically a boiler setting Y .with-a pulverizedfuel handling system em- V heated, or make-up, The features u'sualfto such a system. I have be'fed, as needed, by a suitable mechanism indicated at 9, through burner nozzles 10, -into the furnace chamber', indicated as a whole by the reference-numeral 11. The furnace has the usual boiler tubes 12 and drums 13, and

also a water-screen 14.

From the separator 7.',a return-pipe 15 conducts the air, still bearing a certain quantity of fine coal dust, back to the pulverizer 3.`

From the cycle of Operations just described, where the fuel-carryinglair is continually passed back through the pulverizer in order not to waste what coal may remain in suspension in it,it'is evident that unless the lcoal supplied to the pulverizer is very thoroughly dried the carry-ing air in the system will soon be saturated with moisturev from the coal. j

` rlhe means I have provided for overcom iig this diiiculty consists essentiall "of two conduits and certain valve controls fb them, substantiallyl as follows:

The conduit 16, with its fan 17, taps air from the return side 15, of the system and forces it into the combustion chamber at a suitable point, for instance at the fuel-burner castings 10a. A second conduit 18, draws heated air, either from the space between the `walls of a hollow-wall' furnace or, Vas here shown,l from a point near the bottom 19, ofV the urn ce, in which latter case the supply of. air drawn upon is usually that which en-Vv ters Iby vthe ports 24', especiallyl the lower, ,ones. This heated air is admitted into the return line 15, that is, onI the. air-intake side of thepulverizer 3. Valves 20, 21, 22 and 22?L are provided to regulate the amount of oarrying air withdrawn from, and the amount of air admitted to, the

The numeral 23 at thev top ofthe system.

" In some boiler settings it will be convenient or advantageous to employ, in addition to... the discharging and replenshin conduits, 16 and 18, with their valves, a ranch pipe 25 with valve 26 to divert heated air` directly from the conduitlS to thev primary air fan 17 when little or no air is being tapped from the return pi ve 15.

v The operation o the systeins in this wise,

returnepipe indicates aipressure-relief valve. Y

therefore, thek air which is through the pipe 16, and which in practice arrows indicating the direction of iow of the fuel and air streams:

The fuel admitted to the pulverizer 3, is sent by way of the conduits 4 and 6, through the medium of the fan 5, to the separator 7, and thence to the furnace 11, through the bin '8, feeders 9 and nozzles 10. which the fuel is separated is returned through the pipe 15 to the pulverizer. By continual withdrawal of a certain amount of the air from this return line and a continual substitution of dry, heated, air, the dampness of the system can be readily controlled, and the rate of such substitution will be determinedby the rate at which moisture is being introduced intothe mill by the coal.

1While the amount of moisture absorbed by the air in a closed system, wherein the fuelcarrying air is continually passing back through the pulverizer, is suiicient to saturate this air in a comparatively short time, I have found that when acertain amount of make-up air is admitted to the system the rate of 'absorption of moisture in thel air withdrawn from the system is not so high but that theV withdrawn air can be economically utilized in the furnace itself. I take, withdrawn always contains some .fine coal dust, and admit it into the furnace where itis utilized in the combustionstream.

to be high, and that the air absorbs considerable `moisture therefrom, and as a resulta considerable amount of air is to be drawn from the system; then valve 2l.will be left open, valve 26 closed, and the primary Vair fan 17 will withdraw air from the returnline 15 through the medium of pipe v16.

Heated air, sufficient to take the place of thatv discharged, will be drawn into the system through pipe 18, b the suction of the system created by the exliauster 5, valve 22il being adjusted for this purpose. When the coal used has less moisture, valve 21 will not be opened so wide, and the fan 17 may then'be partly supplied, either with room air drawn in through valve 20, or with .heated air controlled by valve 26, orboth, depending up'on temperature conditions and rate of firing.

The temperature and dryness of the makeup air may be readily controlled by varying the positions of valves 22 and 22a so as to admit any desired proportion of room air with the preheated air.

. must sometimes be admitted to prevent dan- A will draw all gerous over-heating of the conveyor system.

When it is desired toV operate the system without change of the carrying air, valves 21, 22 and 22a will be closed and the fan 17 elsehthrough conduit 25 with its valve 26, or bot J From the foregoing description of theopsumption and direct control The air from Considerable room air its air through valve 20, or

eration of my invention, it is apparent that eiiciency of operation, economy of coal conof the humidity and temperature of the carrying air and of the air admitted to the burners are readily obtained.

I claim:

1. In combination with a furnace, a fuel handling system comprising a pulverizer and separator, conveying means from pulverizer to separator and a return air-pipe from separator to pulverizer, means for conveying fuel from the separator tothe furnace, means for diverting air from the separator to a point of delivery to the furnace, and means adapted to deliver a preheated gaseous medium to said1 diverted air, or to the pulverizer or to bot l 2. In combination with a furnace andan air fan therefor,'a pneumatic conveying system including; a mill and separator, piping from mill to separator, a return line from separator to mill, means for conveyingv fuel from the separator to the furnace, a conduit `for taking air from the return line to the fan,

J ery and return pipes between them, means Assuming the moisture content of the coalL for conveyingfuel from the separator to the furnace, a conduit for taking return air from the system'to the primary air fan, a hot-air pipe from a region of furnace-heated air to the air-intake side of the mill, and a branch pipe from said hot air pipe to the fan.

4. In combination with a furnace and its primary air fan, a' pneumatic conveying system including: a mill and separator, delivery and return pipes between them, means for conveying fuel from the separator to the furnace, a conduit to supply air from the return side of the separator to the primar air fan, a second conduit from a region o furnaceheated air to the air-intake side of the mill; a shut-oli valve in each conduit, a valve controlled'port to theatmosphere in each conduit, and a valve-controlled by-pass from the region of heated air to the fan.

5. In combination, a pulverized fuel burning furnace, a closed circulatory fuel pulverizing and separating system' therefor including a delivery line from pulverizer to separator and a return conduit from separator to pulverizer, means for conveying fuel from the separator to the furnace, means for sup- -plying air heated by the furnace to the return conduit, and means for withdrawin air from said conduit and delivering it to saiii furnace.

6. In combination, a pulverized fuelburning furnace,.a closed circulatory fuel pulverizing and separating system therefor includ- 4 tor and a return conduit from separator to plying air pulverizer, means for conveying fuel from the separator to the furnace, means for supheated by the furnace to the return conduit, and means for withdrawing air from said conduit at a point between the separator and the point of entrance of the heatedair thereto and for delivering it to the furnace.

n testimony whereof, I have hereunto signed my name.

ROGER D. DE WOLF. 

